This is not my computer, it is a friend's but whenever he turns the plug on the wall on, the computer turns on automatically. It is a Dell Dimension 8300 and I remember having the same problem with my old Dell Dimension XPS T700R. Is it a BIOS setting? I just ignored it on my PC but it would be good to know if the problem can be fixed. If it is the power supply then I can replace it. Thanks for any advice.

EDIT: Also the computer can no longer keep time (thinks its 2004), this is probably the clock battery on the motherboard isn't it?

yes i blieve it is the psu i tried another one on a pc that was doing that and it somewhat fixed it, it may be a board problem and yes that is the cmos battery you can pick one up at any store just replace it..

This is not my computer, it is a friend's but whenever he turns the plug on the wall on, the computer turns on automatically. It is a Dell Dimension 8300 and I remember having the same problem with my old Dell Dimension XPS T700R. Is it a BIOS setting? I just ignored it on my PC but it would be good to know if the problem can be fixed. If it is the power supply then I can replace it. Thanks for any advice.

EDIT: Also the computer can no longer keep time (thinks its 2004), this is probably the clock battery on the motherboard isn't it?

It's a feature of many computers, to turn on the first time after being plugged in automatically, usually you can enable / disable it in the BIOS.